butter, to grease pan
2 cups rolled oats
2 1/4 cups flour (all purpose, rye or whole wheat)
1 3/4 teaspoons baking soda
1 1/4 teaspoons fine-grain sea salt
1 3/4 cups / 415 ml buttermilk, plus more if needed, and 2T. for brushing (Or, if you are like me, and living in the land of no buttermilk, use 1 cup plain yogurt, and 3/4 cup milk)
mixed seeds - sesame, caraway, poppy, etc.